This invention relates to a deployment inhibiting arrangement for a thrust reverser system and to a thrust reverser system including such an arrangement.
During maintenance of an aircraft jet engine on the ground, it is important, for safety reasons, to ensure that the engine thrust reverser cannot be deployed inadvertently, in order to miminimise the risk of injury to personnel. In some conventional arrangements, an inhibit device operates to prevent the usual electro-hydraulic control system from signalling deployment of the thrust reverser. Such arrangements can pose practical problems of operation at ground level and also leave open the possibility of the signal inhibiting device being inadvertently overridden, leaving the system in a potentially hazardous actuable condition.
An object of the present invention is to provide an improved arrangement for inhibiting operation of an aircraft jet engine thrust reverser system, in which the aforesaid drawbacks are alleviated or avoided.
According to the invention, there is provided a deployment inhibiting arrangement for a jet engine thrust reverser system, the system including one or more actuators for operating a thrust reverser of the system and first locking means for the or each actuator normally serving to hold the system in a condition in which the thrust reverser is undeployed, the inhibiting arrangement including additional locking means normally held in an inactive condition, but operable by means independent of said one or more actuators and first locking means to provide an additional mechanical lock serving to prevent deployment of the thrust reverser irrespective of the condition of the first locking means and/or actuator(s).
Preferably, the additional locking means comprises a locking member operatively associated with said one or more actuators, or means associated with the latter, and one or more locking elements, each movable between locking and unlocking positions in which it is respectively in and out of locking engagement with the locking member, the or each locking element being normally held in its unlocking position by a retainer which is movable by a control device operable externally of the engine to a position in which it permits movement of the or each locking element to its locking position to prevent operation of the or each actuator.
In one convenient arrangement, a plurality of thrust reverser actuators are provided and interconnected, for synchronous operation, by a synchronising shaft, and the locking member is drivingly connected to the synchronising shaft and arranged for locking co-operation with said one or more locking elements to prevent rotation of said shaft and thereby prevent operation of the actuators.
Preferably, the retainer is spring-urged towards its operative position and is operatively associated with a cam element connected to tie control device, the cam element being engageable with the retainer by operation of the control device so as to move the retainer from its operative position to permit said locking element or elements to move into locking engagement with the locking member.
The invention further resides in a jet engine thrust reverser system including one or more actuators for operating a thrust reverser of the system and first locking means for the or each actuator normally serving to hold the system in a condition in which the thrust reverser is undeployed, and a deployment inhibiting arrangement including additional locking means normally held in an inactive condition, but operable by means independent of said one or more actuators and said first locking means to provide an additional mechanical lock serving to prevent deployment of the thrust reverser irrespective of the condition of the first locking means and/or actuator(s).
The invention still further resides in a jet engine trust reverser system including a plurality of actuators for operating a thrust reverser of the system and first locking means for the actuators normally serving to hold the system in a condition in which the thrust reverser is undeployed, a synchronising shaft which in use interconnects said actuators for synchronous operation, and a deployment inhibiting arrangement including additional locking means normally held in an inactive condition, but operable by means independent of said actuators and said first locking means to provide an additional mechanical lock serving to prevent rotation of said shaft and thereby prevent operation of the actuators and so prevent deployment of the thrust reverser irrespective of the condition of the first locking means and/or actuators.